The present disclosure relates to semiconductor light-emitting systems used for displays such as projectors and laser processors. More particularly, the present disclosure relates to nitride semiconductor light-emitting systems including nitride semiconductor light-emitting devices, which emit light with high light intensity and a wavelength within the range from ultraviolet light to blue light.
Nitride semiconductor light-emitting systems including nitride semiconductor light-emitting devices such as semiconductor lasers are being actively developed as light sources of image display devices such as laser displays and projectors, as well as light sources of industrial processors such as laser scribing apparatuses and annealing apparatuses for thin films. The light emitted from the nitride semiconductor light-emitting devices has a wavelength ranging from ultraviolet light and blue light, and sometimes an extremely great optical output over 1 watt. Innovative approaches are thus needed for packages mounting the nitride semiconductor light-emitting devices.
In view of the background, for example, as described in Japanese Unexamined Patent Publication No. 2009-135235, conventional nitride semiconductor light-emitting systems have employed package configurations similar to those in the semiconductor light-emitting systems mounting semiconductor lasers emitting light with a wavelength within the range from infrared light to red light. Specifically, in a semiconductor light-emitting system, a semiconductor light-emitting device is mounted on a metal base mount, and then enclosed by a cap member with a light-transmitting window. This configuration seals the semiconductor light-emitting device from the outside to radiate heat from the semiconductor light-emitting device, and to extract light from the semiconductor light-emitting device to the outside. First, such a conventional semiconductor light-emitting system will be described below with reference to FIG. 11.
A conventional semiconductor light-emitting system 1000 includes a semiconductor laser device 1030, a sub-mount 1010, a package 1040, and a cap member 1100. The package 1040 includes a stem 1001 made of an iron-based material, a block 1002 of oxygen-free copper attached onto the stem 1001, lead pins 1004 and 1005 respectively attached to through-holes 1001a and 1001b of the stem 1001 via insulating rings 1020 made of glass, and a lead pin 1003 directly attached to the stem 1001. The semiconductor laser device 1030 is mounted in the block 1002 via the sub-mount 1010, and is electrically connected to the lead pins 1004 and 1005 by two wires 1008 and 1009. The cap member 1100 includes a metal cap 1103 made of kovar, and a light-transmitting window 1104 of glass fixed by low-melting glasses 1105. The metal cap 1103 includes cylindrical side walls 1101, a top surface 1102 closing one ends of the side walls 1101 and having an emitting hole 1102a extracting laser light from the semiconductor laser device 1030 to the outside. The metal cap 1103 further includes flanges 1103a disposed at the other ends of the sidewalls 1101 to adhere the cap member 1100 to the upper surface of the stem 1001, on which the semiconductor laser device 1030 is disposed, by resistance welding. At the emitting hole 1102a, the light-transmitting window 1104 is attached to the top surface 1102 to close the opening.
On the other hand, different from this package configuration, Japanese Unexamined Patent Publication No. 2001-358398 suggests a package configuration with high heat radiation and airtightness. A conventional semiconductor light-emitting system 2000 will be described below with reference to FIG. 12. In the semiconductor light-emitting system 2000, welding-aids 2015 are fixedly formed in a stem 2001 of a package 2040, which fixes a semiconductor laser device 2030, at the portion welded and joined to a cap 2100 by silver brazing. The cap 2100 is welded and joined to the welding-aids 2015. Since the stem 2001 is then jointed to the cap 2100 via the welding-aids 2015, the material of the stem 2001 can be selected regardless of the weldability between the cap 2100 and the stem 2001. As a result, heat generated from the semiconductor laser device 2030 is efficiently radiated outside via a sub-mount 2010, a device fixing block 2002, and the stem 2001, thereby improving the radiation of the heat generated in the semiconductor laser device 2030.